Abstract: Disclosed is a butterfly valve having a seat, when viewed in cross-section, of generally U-shaped configuration, and an insert configured with appropriately shaped cooperating surfaces. The sealing effectiveness of the valve is enhanced by line pressure regardless of the direction of application of such pressure, the torque characteristics of the valve are relatively low, the ability to withstand temperature cycles is good, and the seat is restrained from destructive interference with the disc.

Abstract: A locking device for a valve disposed in a housing including a stem assembly projecting from the valve for rotation of the valve between an open and closed position which includes a handle assembly provided with a handgrip portion at a first end thereof and a securing member at a second end thereof connected to the stem assembly. The locking device also provides for an abutment member mounted on the housing as well as a locking member mounted on the handle assembly so as to interfittingly cooperate with the handle assembly securing member and the abutment member to secure the valve in either the open or the closed valve position.

Abstract: A valve seat insert is disclosed which is useful in a butterfly valve of the type disclosed and claimed in U.S. Pat. No. 3,608,861. In such valves, disc and sealing ring contact pressure is enhanced by fluid pressure in the fluid line regardless of the direction of fluid pressure. The valve seat mechanism provides a fulcrum to control deflection of the seat ring when the seat is pressurized from the stem side, and also, by means of an insert with a locking ridge, limits undesirable inward radial movement of the seat ring.